Sintered porous body with multiple layers

Abstract

Described are porous, sintered inorganic bodies that include multiple layers made from different types of metal particles, that may be useful as filter membranes, and also to methods of making and using the porous, sintered inorganic bodies.

1 . A porous membrane comprising:
 a first layer comprising a combination of sintered inorganic particles comprising:
 coarse particles having a particle size of at least 10 microns and a coarse particle sintering point, and 
 first fine particles having a particles size of at least 1 micron and a first fine particle sintering point below the coarse particle sintering point, and 
   a second layer comprising a combination of sintered inorganic particles comprising:
 second fine particles having a particle size of at least 1 micron and a second fine particle sintering point below the coarse particle sintering point, and 
 nanoparticles having a particle size below 1 micron and a nanoparticle sintering point above the first fine particle sintering point and above the second fine particle sintering point. 
   
     
     
         2 . The membrane of  claim 1 , wherein the coarse particles have a particle size in a range from 10 to 200 microns. 
     
     
         3 . The membrane of  claim 1 , wherein:
 the first fine particles have a particle size in a range from 1 to 10 microns, and   the second fine particles have a particle size in a range from 1 to 10 microns.   
     
     
         4 . The membrane of  claim 1 , wherein the nanoparticles have a size in a range from 0.001 to 0.5 micron. 
     
     
         5 . The membrane of  claim 1 , wherein,
 the first fine particles comprise nickel or a nickel alloy,   the second fine particles comprise nickel or a nickel alloy,   the coarse particles comprise nickel or a nickel alloy, and   the nanoparticles comprise stainless steel.   
     
     
         6 . (canceled) 
     
     
         7 . The membrane of  claim 1 , wherein,
 the first fine particles comprise stainless steel,   the second fine particles comprise stainless steel,   the coarse particles comprise stainless steel, and   the nanoparticles comprise titanium, titanium alloy, alumina, or zirconia (ZrO 2 ).   
     
     
         8 . (canceled) 
     
     
         9 . The membrane of  claim 1 , wherein the first layer comprises:
 from 50 to 70 weight percent coarse particles, and   from 30 to 50 weight percent first fine particles.   
     
     
         10 . The membrane of  claim 1 , wherein the second layer comprises:
 from 40 to 75 weight percent second fine particles, and   from 25 to 60 weight percent nanoparticles.   
     
     
         11 . The membrane of  claim 1 , comprising:
 from 50 to 75 weight percent first layer, and   from 25 to 50 weight percent second layer.   
     
     
         12 . The membrane of  claim 1 , wherein
 the first fine particles are dendritic, and   the second fine particles are dendritic.   
     
     
         13 . The membrane of  claim 1 , wherein the membrane comprises a tube. 
     
     
         14 . (canceled) 
     
     
         15 . (canceled) 
     
     
         16 . The membrane of  claim 1 , wherein the membrane has a bubble point of at least 25 pounds per square inch as measured by ASTM E 128-99 (2019), measured by using 60/40 isopropyl alcohol (IPA)/water. 
     
     
         17 . A filter assembly comprising a filter housing that contains a filter membrane of  claim 1 . 
     
     
         18 . A method of processing supercritical carbon dioxide, the method comprising passing supercritical carbon dioxide through a membrane of  claim 1 . 
     
     
         19 . A method of forming a porous membrane, the method comprising:
 preparing a precursor comprising a first blend of inorganic particles comprising:
 coarse particles having a particle size of at least 10 microns and a coarse particle sintering point, and 
 first fine particles having a particles size of at least 1 micron and a first fine particle sintering point below the coarse particle sintering point; and 
   applying a second blend of inorganic particles to a surface of the precursor, the second blend comprising
 second fine particles having a particle size of at least 1 micron and a second fine particle sintering point below the coarse particle sintering point, and 
 nanoparticles having a particle size below 1 micron and a nanoparticle sintering point above the first fine particle sintering point and above the second fine particle sintering point. 
   
     
     
         20 . The method of  claim 19 , further comprising:
 compressing the first blend of inorganic particles to form a first green body,   applying the second blend of inorganic particles to the first green body,   compressing first green body and second blend of inorganic particles to form a second green body, and   sintering the second green body.   
     
     
         21 . The method of  claim 20 , wherein sintering comprises increasing a temperature of the second green body such that:
 the first fine particles and the second fine particles begin sintering before the coarse metal-particles begin sintering, and   the first fine particles and the second fine particles begin sintering before the nanoparticles begin sintering.   
     
     
         22 . The method of  claim 21 , wherein the coarse particles begin sintering before the nanoparticles. 
     
     
         23 - 25 . (canceled) 
     
     
         26 . The method of  claim 20 , the membrane having a bubble point of at least 25 pounds per square inch as measured by ASTM E 128-99 (2019), measured by using 60/40 isopropyl alcohol (IPA)/water. 
     
     
         27 . A tubular porous membrane comprising:
 coarse particles having a particle size of at least 10 microns,   fine particles having a particles size of at least 1 micron, and   nanoparticles having a particle size below 1 micron,   
       wherein the porous membrane has:
 a bubble point of at least 30 pounds per square inch as measured by ASTM E 128-99 (2019), measured by using 60/40 isopropyl alcohol (IPA)/water, 
 an air flux value of a least 0.07 slpm/cm2 at 30 psi, and 
 a radial crush test value of at least 35 kilopounds per square inch measured using ASTM B939-21. 
 
     
     
         28 . (canceled) 
     
     
         29 . (canceled)